engineering field firing exercise b3l4258 … · 2016-12-30 · assistance of explosive ordnance...

UNITED STATES MARINE CORPS THE BASIC SCHOOL

MARINE CORPS TRAINING COMMAND CAMP BARRETT, VIRGINIA 22134-5019

ENGINEERING FIELD FIRING EXERCISE

B3L4258 STUDENT HANDOUT

Basic Officer Course

B3L4258 Engineering Field Firing Exercise

2 Basic Officer Course

Topic Page

Military Explosives 4

Demolition Charges 6

Specialized Demolition Charges 7

Demolition Accessories 11

Firing Systems 16

Safety Precautions 21

Summary 22

References 22

Glossary of Terms and Acronyms 22

Notes 23

Military Explosives

Introduction Understanding and properly employing demolitions can mean the difference between mission accomplishment or failure. Using explosives requires much knowledge and responsibility, extensive and thorough planning, and, in some circumstances, patience.

Importance The importance of a working knowledge of military explosives is demonstrated in the following synopsis from the book, The Bridge at Dong Ha.

On Easter Sunday, 1972, two North Vietnamese infantry

divisions, more than 200 T-54 tanks, and supporting units attempted to cross the Cua Viet River over the bridge near the village of Dong Ha, eight miles south of the DMZ. The Easter Offensive was to be the push to ultimately capture Saigon. With his knowledge of military explosives, Captain John W. Ripley, 0302/USMC, serving as an advisor to the 3rd Battalion Vietnamese Marine Corps, halted the North Vietnamese offensive. Captain Ripley successfully placed and detonated over 300 pounds of TNT and C-4 to destroy a section of the steel and timber bridge at Dong Ha. The North Vietnamese were unable to launch another large offensive to capture Saigon for another three years.

In This Lesson You will learn the various types of explosives, their intended usage, and how to safely and effectively prepare them for use.

This lesson covers the following topics:

Learning Objectives Terminal Learning Objectives

Given an M18A1 Claymore mine and sector of fire, while wearing a fighting load, describe how to emplace an M18A1



Claymore mine to ensure the sector of fire is covered without endangering friendly personnel or equipment. (0300-DEMO-1003)

Given a unit, an assault or engineer unit, demolitions, a mission, and a commander's intent, employ demolitions to achieve desired effects of the demolitions in support of the ground scheme of maneuver. (0302-OFF-1206)

Given a unit, a barrier plan, and material needed to emplace obstacles, direct obstacle emplacement to achieve the effect desired by the commander. (MCCS-DEF-2203)

Enabling Learning Objectives

Given a unit, a mission, a mental estimate of the situation, supporting engineer assets, and a commander's intent, employ engineers in support of defensive operations to accomplish the mission. (0302-DEF-1301e)

Without the aid of references, describe engineer capabilities that support offensive operations to support mission accomplishment. (0302-OFF-1201g) Without the aid of references, describe the four functional areas of combat engineering without error. (0302-OFF- 1201h)

Without the aid of reference, identify demolition capabilities/limitations without error. (0302-OFF-1206b) Without the aid of reference, identify obstacle types without error. (MCCS-DEF-2203a)

Given a mission, a commander's intent, obstacle materials, and while leading a rifle squad or platoon, plan obstacles to support the defensive scheme of maneuver. (MCCS-DEF- 2203b)

.



Military Explosives

Explosives. Explosives are substances that, through chemical reaction, violently change to a gaseous form. In doing so, they release pressure and heat equally in all directions. The table below describes the two major categories of explosives.

Category Description

Low explosives

• Change from solid to gaseous state slowly over a sustained period (1300 feet/second)

• Are ideal when a pushing or shoving effect is required

High explosives

• Change from solid to gaseous state almost instantaneously (3280 to 28,880 feet/second)

• Produce a shattering effect on the target

Military Explosives. To be suitable in military operations, explosives must:

• Be:

o Produced from readily available raw materials o Inexpensive to manufacture o Suitable for use under water or in a damp climate o Conveniently sized and shaped for packaging, storing, distribution, handling, and

emplacing by troops o Assigned a relative effectiveness factor (a ratio that compares the effectiveness

of any given military explosive to the effectiveness of TNT) • Have:

o Relative insensitivity to shock or friction, yet able to be positively detonated by

easily prepared initiators o A shattering effect (Brisance) and potential energy adequate for the purpose o The stability adequate to retain usefulness for a reasonable time when stored in

any climate at temperatures between –80 degrees Fahrenheit (F) and 165 degrees F

o High density (weight per unit of volume) o Minimum toxicity (poisonous effect) when stored, handled, and detonated o A high energy output per unit of volume

CAUTION: Since explosives contain their own oxidizer, burning explosives cannot be extinguished by smothering. Whenever explosives burn, possible detonation poses a hazard. Personnel should not attempt to extinguish burning explosives without competent supervision and the advice and assistance of explosive ordnance disposal (EOD) personnel.



Military Explosives (Continued)

Characteristics of US Explosives. The table below lists the characteristics and principal uses of US explosives.

Explosive

Principal Uses

Velocity of Detonation

Relative Effectiveness as a Breaching Charge

(TNT – 100)

Intensity of Poisonous

Fumes

Water

Resistance (m/sec) (ft/sec)

Black powder Time blasting fuse 400 1,300 0.55 Dangerous Poor Ammonium nitrate Demolition charge (cratering) 2,700 8,900 0.42 Dangerous Poor Amatol 80/20 Bursting charge 4,900 16,000 1.17 Dangerous Poor Military dynamite, M1

Demolition charge (quarrying, stumping, and ditching)

6,100 20,000 0.92 Dangerous Fair

Detonating cord Priming 6,100 to

7,300

20,000 to

24,000

Excellent

TNT • Demolition charge

(breaching)

• Composition explosives

6,900 22,600 Dangerous Excellent

Tetrytol 75/25 Demolition charge (breaching) 7,000 1.2 Dangerous Excellent Tetryl • Booster charge


7,100 1.2 Dangerous Excellent

Sheet explosive M118 and M186

Demolition charge (cutting) 7,300 2,400 1.14 Dangerous Excellent

Pentolite 50/50 • Booster charge

• Bursting charge

7,450 24,400 Dangerous Excellent

Nitroglycerine Commercial dynamites 7,700 25,200 1.5 Dangerous Good Bangalore torpedo, M1A2

Demolition charge (wire and minefield breaching)

7,800 25,600 1.17 Dangerous Excellent

Shaped charges M2A3, M2A4, and M3A1

Demolition charge (cutting holes)


Composition B Bursting charge 7,800 25,600 1.35 Dangerous Excellent Composition C4 and M112

Demolition charge (cut and breach)

8,040 26,400 1.34 Slight Excellent

Composition A3 • Booster charge

• Bursting charge

8,100 26,500 Dangerous Good

PETN • Detonating cord

• Blasting caps

• Demolition charges

8,300 27,200 1.66 Slight Excellent

RDX • Blasting caps





Demolition Charges

Demolition Charges. The table below lists the principle uses, advantages, and limitations as well as a diagram of three demolition charges (refer to the Characteristics of US Explosives table, page 5, for their characteristics).

Charge Principle Uses Advantages Limitations

Trinitrotoluene (TNT)

• Standard demolition charge for all types of demolition work

• The ¼-pound charge

used primarily for training

• Has a high detonating velocity

• Is

o Stable o Relatively insensitive to

shock or friction

o Water resistant o Convenient in size,

shape, and packaging

• Cannot be molded

• Is difficult to use on

irregularly shaped targets Not recommended for use in closed spaces (explosion produces poisonous gases)

TNT M112 Block Demolition Charge (C-4)

• Primarily for

o Cutting o Breaching o All types of demolition

work

• Because of high shattering

effect, ideally suited for cutting steel and other hard materials

• Can be cut and molded to fit irregularly shaped targets

• Adhesive backing allows charge to be attached to any relatively flat, clean, dry surface above the freezing point

• Paper color aids in camouflage

• Odd weight, 1.25

versus 1 pound (calculating charge weight is difficult)

• Adhesive backing will

not adhere to wet, dirty, rusty, or frozen surfaces

M112 Block Demolition Charge



Demolition Charges (Continued)

Forty Pound

Ammonium Nitrate Block Demolition Charge (Cratering)

• Suitable for

o Cratering operations o Ditching operations

• Has been designed as a standard cratering charge

• Can also be used in destroying

o Buildings o Fortifications o Bridge abutments

• Size and shape of charge makes it ideal for cratering operations

• Is inexpensive to produce

compared to other explosives

• Ammonium nitrate absorbs moisture

• When wet, is impossible to detonate (to ensure detonation use only metal containers showing no evidence of water damage)

• Detonate all charges

placed in wet or damp boreholes as soon as possible

Forty Pound Ammonium Nitrate Block Demolition Charge (Cratering)

Specialized Demolition Charges and Assemblies

Shaped Charge. The table below lists the principle uses, advantages, and limitations as well as a diagram of the shaped charge (refer to the Characteristics of US Explosives table, page 5, for its characteristics).

Principle Uses Advantages Limitations

• Primarily to bore holes in

o Earth o Metal o Masonry o Concrete o Paved and unpaved roads

• Effectiveness depends largely on o Target’s shape and

material (what it is made of) o Explosive and

emplacement

Strong penetration capabilities

Not effective

• Under water

• When foreign objects are present inside the conical cavity (prevents a narrow jet from forming)



Specialized Demolition Charges and Assemblies (Continued)

15 and 40 Pound Shape Charge

M183 Demolition Charge Assembly (Satchel Charge). The table below lists the characteristics and principal uses as well as a diagram of the M183 demolition charge assembly (satchel charge).

Characteristics Principle Uses

• Consists of

o M112 (C-4) demolition blocks – 16 total o Priming assemblies – 4 total

• Total explosives weight is 20 pounds

• Demolition blocks are packed in two bags of 8 blocks per bag

• Bags are housed in an M85 canvas carrying case

• Primarily in breaching obstacles

• Demolition of structures where large demolition charges are required

M183 Demolition Charge Assembly




Bangalore Torpedo Demolition Kit. The table below lists the characteristics and principal uses as well as a diagram of the Bangalore torpedo demolition kit.

Characteristics Principle Uses

• Each is o 5 feet long o Weighs approximately 15

pounds (total)

• Contains

o 10 pounds Composition B4 o 1 pound Composition A3 as a

booster

• Each kit consists of 10 torpedoes (loading assemblies)

• To clear paths through o Wire entanglements

o Minefields o Heavy undergrowth o Bamboo

• Clears a path approximately 3 to 4 meters wide through wire entanglements

• In minefield breaching, will explode o All antipersonnel mines o Most of the antitank mines in a

narrow footpath approximately 1 meter wide

Bangalore Torpedo Demolition Kit




M18A1 Claymore (Directional Fragmentation) Anti-Personnel Mine. The table below lists the characteristics, functioning, and effects of the M18A1 claymore (directional fragmentation) anti-personnel mine (see diagram below).

Characteristics • Contains

o 1.5 pounds of C-4 explosive o 700 steel pellets encased in plastic

• Is equipped with 33 meters of firing wire attached to an electric blasting cap and an M57 power source (clacker) (which provides only enough power to detonated at 33 meters)

• If distance is increased, use an alternate power source, wire, and cap

• One out of six contains a tester (to ensure the firing wire, electric cap, and M57 clacker are functioning properly)

Functioning Command detonated using the M57 clacker Effects • Designed to deliver

o Lethal steel ball bearings o In a fan-shaped pattern o Over a designated target area

• Effective casualty radius is

o 50 meters in a 60-degree arc o 2 meters high with a forward danger area of 250 meters

• Minimum back and side blast safety distances are

o 16 meters in a covered position o 100 meters in an uncovered position

M18A1 Claymore Mine



Demolition Accessories

Demolition Accessories.

Time Fuse. The M700 fuse (see diagram below) is a dark green cord, 0.2 inches in diameter, with a plastic cover. Depending on the time of manufacture, the cover may

• Be smooth

• Have single yellow bands around the outside at 12- or 18-inch intervals and double yellow bands at 60- or 90-inch intervals (bands are provided for easy measuring)

The outside covering becomes brittle and cracks easily in arctic temperatures. The burning rate is approximately 40 seconds per foot.

Detonating Cord. The table below lists the characteristics and principal uses, as well as a diagram of detonating cord.

Characteristics Principal Uses

• Core of PETN or RDX explosive in a textile tube coated with a thin layer of asphalt

• On top of this layer of asphalt is an outer textile cover finished with a wax gum composition or plastic coating

• Transmits a detonating wave from one point to another at a rate between 20,000 to 24,000 feet per second

• A partially submerged, water soaked detonating cord will detonate if initiated from a dry end

• When exposed to low temperatures

o Does not lose explosive properties o Covering becomes stiff and cracks when bent

• Use great care when using detonating cord primers in arctic conditions

• To prime and detonate other explosive charges

• When its explosive core

is detonated by a blasting cap or other explosive device, detonating cord transmits the detonation wave to an unlimited number of explosive charges



Demolition Accessories (Continued)

Detonating Cord

Blasting Caps. The table below describes and diagrams: • Electric blasting caps

• Non-electric blasting caps

Electric Blasting Caps

• Use when a source of electricity such as a blasting machine or battery, is available

• Lead wires are 12 feet long

• For ignition, requires 1½ amperes of electricity passing through their wires

Electric Blasting Cap

Non-Electric Blasting Caps

• May be initiated by a

o Time blasting fuse o Firing device and detonating cord

• Because they are difficult to waterproof, when possible, avoid using to prime charges placed

o Underwater o In wet boreholes

• If necessary, use moisture-proof non-electric blasting caps with a waterproof sealing compound




Non-Electric Blasting Cap

M81 Weatherproof Fuse Igniter. The M81 weatherproof fuse igniter (see diagram below) is designed to ignite a time blasting fuse in all sorts of weather conditions, even underwater if properly waterproofed. The fuse is inserted through a sealing rubber grommet and into a split collet, which secures the fuse when the end cap on the igniter is tightened. A pull on the pull ring releases the striker assembly, allowing the firing pin to drive against the primer, which ignites the fuse.

M81 Fuse Igniter




M1A4 Priming Adapter. The M1A4 priming adapter (see diagram below) is a plastic, hexagonal shaped device threaded to fit threaded cap wells. A shoulder inside the threaded end is large enough for a time blasting fuse and detonating cord, but too small for a military blasting cap. The adapter is slotted lengthwise to permit easy, quick insertion of the electric cap lead wires.

Priming Adapter

M2 Cap Crimpers. The M2 cap crimper (see diagram below) is used to squeeze the shell of a non-electric blasting cap around a

• Time fuse

• Standard base

• Detonating cord securely enough to keep it from being pulled off, but not tight enough to interfere with the burning of the powder train in the fuse of the detonating cord. One leg of the handles is pointed to use in punching cap wells in explosive material for easy insertion of the blasting cap. The other leg is a screwdriver end. Use the cutting jaw for cutting fuse and detonating cord only.

M2 Cap Crimpers




M51 Test Set. Use an OHM meter (see diagram below) to test the continuity of an electrical circuit.

M51 Test Set

Blasting Machine. Use the blasting machine (see diagram below) to provide the electric impulse needed in electric blasting operations. The two types of blasting machine are the:

• M32 blasting machine, capable of producing enough electricity to set off up to 10

blasting caps

• M34 blasting machine, capable of setting off up to 50 blasting caps

Both blasting machines are small, lightweight, and impact resistant.

Blasting Machine



Firing Systems

Firing Systems. Non-Electric Firing System. A non-electric system (see diagram below) is one in which an explosive charge is prepared for detonation by means of a non-electric blasting cap. The basic priming materials consist of

• A non-electric blasting cap, which provides the shock adequate to detonate the

explosive

• A time fuse, which transmits the flame that fires the blasting cap

• A fuse igniter, which initiates the firing system

Non-Electric Firing System

The table below lists the steps to prepare a non-electric firing system.

Step Action 1 Test burn time fuse. 2 Prepare time fuse to necessary length. 3 Attach fuse igniter. 4 Crimp blasting cap to time fuse (see diagram below).

Crimping

5 Insert blasting cap into explosive. 6 Light time fuse.



Firing Systems (Continued)

For non-electric misfires, • Delay investigation for at least 30 minutes.

• If the misfire charge is:

o Not tamped, do not move or disturb it. Lay a primed one-pound charge on the misfired charge and fire.

o Tamped:

− One foot or less, place a two-pound charge on top

− More than one foot, carefully remove tamping material. Lay a primed one- pound charge on the misfired charge and fire

Electric Firing System. An electric firing system (see diagram below) is one in which electricity is used to fire the primary initiating element. An electric impulse supplied from a power source, usually an electric blasting machine, travels through the firing wire and cap lead wires to fire an electric blasting cap. The chief components of the system are the:

• Electric blasting cap

• Firing wire

• Blasting machine or battery or alternate power source

Electric Firing System

The table below lists the steps to prepare an electric firing system.

Step Action

1 Lay out and test firing wire. 2 Test blasting caps. 3 Connect caps to circuit. 4 Insert caps into charges. 5 Test entire circuit. 6 Test blasting machine. 7 Connect blasting machine to circuit. 8 Fire.




For electric misfires:

• Take corrective action immediately

• Check the firing wire connection to power source to be sure the contacts were good

• Try two or three more times to fire

• Use another power source

• When employing:

o Only one electrical blasting cap:

− Disconnect the blasting machine

− Shunt wires (twist wires together)

− Investigate immediately

o More than one electrical blasting cap, wait 30 minutes before inspecting.

• Check entire circuit

• Replace shot wire/cap

• Initiate detonation

Detonating Cord Priming. Alternate Tie #2. The table below lists the steps for Alternate Tie #2 (TNT only).

Step Action

1 Place a loop of detonating cord on the explosive (see diagram below).

Alternate Method #2 2 Wrap the cord four to six times around the explosive. Be sure the first wrap goes immediately

over the short leg of the loop, wrapping towards the loop. 3 Insert the running end through the eye of the loop. 4 Tighten the knot by pulling on the short leg.




Overhand Knot (C-4). Insert the knot into the explosive or molded piece of explosive. Be sure at least ½-inch of explosive is on all sides of the knot (see diagram below).

Overhand Knot

Branch Line Connections. Fasten a branch line to a main line with a girth hitch with one extra turn (see diagram below).

Girth Hitch with Extra Turn




Trunk Line. Place a single strand of detonating cord down the center of charges (see diagram below).

Trunk Line

Ring Main. Make a ring main by: • Bringing the main line back in the form of a loop

• Attaching the main line to itself with a girth hitch with one extra turn

A ring main will detonate an almost unlimited number of charges. The ring main makes the detonation of all charges more positive because the detonating wave approaches the branch lines from both directions. The charges will be detonated even if there is one break in the ring main.



Safety Precautions

General Safety Precautions for Handling Military Explosives.

• Do not detonate demolitions electrically during any electrical, dust, sand, or snow

storm of a severity great enough to produce atmospheric static electrical charges or when such a storm is within three miles.

• Do not work with electric blasting caps while wearing static electricity-producing clothing (nylon, silk).

• Do not ingest any explosive material.

• Do not get in the smoke of burning explosives. The vapors are toxic if inhaled. Additionally, the smoke will penetrate ordinary clothing and may result in severe dermatitis.

• When placing charges underground, do not bury blasting caps (instead use detonating cord).

• Carry blasting caps in approved containers and keep them out of the direct rays of the sun.

• Within 100 feet of an area in which explosives are being handled or used, do not permit:

o Smoking o Matches o Other sources of fire or flame

• Never kink a time fuse.

• Before investigating non-electric misfires, wait 30 minutes.

• Before firing any charge, always sound off, “Fire in the hole!” three successive times.

• Use only crimpers to crimp blasting caps.

• Do not store or transport caps with high explosives.

• Before unwinding your electrical reel, always be sure the person in charge has the power source.



Summary

Handling explosives requires responsibility and knowledge. They must be treated with respect and never abused. If an explosive charge is not prepared correctly and an attempt to initiate the explosive fails someone now has to approach the explosive to render it safe for others and/or to accomplish the mission.

References

Reference Number or Reference Title Author

FM 5-100 Engineers in Combat Operations

FM 5-101 Mobility

FM 5-102 Counter-mobility

FM 5-103 Survivability FM 5-250 Explosives and Demolitions FM 5-34 (MCRP 3-17A) Engineer Field Data

FM 23-23 FM 20-32

Antipersonnel Mine M18A1 Claymore Mine/Countermine Operations

MCWP 3-31.2 Mine Warfare MCWP 3-17 MAGTF Engineer Operations

MCWP 3-17.3 MAGTF Breaching Operations

Glossary of Terms and Acronyms

Term or Acronym Definition or Identification Explosives Explosives are substances that, through chemical reaction,

violently change to a gaseous form. In doing so, they release pressure and heat equally in all directions.

Low Explosives Change from solid to gaseous state slowly over a sustained period (1300 feet/second) and are ideal when a pushing or

shoving effect is required

High Explosives Change from solid to gaseous state almost instantaneously (3280 to 28,880 feet/second) and produce a shattering effect on the target

Non-Electric Firing System

A non-electric system is one in which an explosive charge is prepared for detonation by means of a non-electric blasting cap.

Electric Firing System An electric firing system is one in which electricity is used to fire the primary initiating element. An electric impulse supplied form a power source, usually an electric blasting machine, travels through the firing wire and cap lead wires to fire an electric blasting cap.

EOD Explosive Ordinance Disposal



Notes

engineering field firing exercise b3l4258 … · 2016-12-30 · assistance of explosive ordnance...

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